IMPULSE

Control system for the group of bell-shaped thermic furnaces process technology

Purpose

The system is developed for automatic control of tempering mode of steel cylinders in the bell-shaped thermic furnaces.

Tempering is a type of steel thermal processing after which the material becomes fit for the most necessary applications. The process of tempering itself is keeping a steel cylinder in a furnace according to the set temperature schedule during one and a half or two days, temperature deviation must not exceed 5 C0.

Automation object is the group of four bell-shaped thermic furnaces. The heat to the furnaces working area is supplied by four speed gas-jets working in the pulse mode. The furnace has a flue gases recirculation circuit.

The tempering is carried out on a steel setting weight up to 15 ts, which is the 1-2 cylinders diameter 300-700 mm and up to 5400 mm long laying flat on stands located on the furnace"s floor.

Basic functions

• reaching the temperature condition set by the operator.
  
• regulating the temperature in the furnace within the period set by the operator (control for gas-jets)
  
• sustaining optimal gas pressure.
  
• sustaining optimal air pressure.
  
• data receipt and transmitting to the operator"s control board (upper level PC).
  
• data receipt and transmitting to the local control board (display on the door of the control panel).
  
• gas supply cut-off in case gas pressure exceed the permissible level (switching off the power supply also leads to gas cut-off).
  
• emergency adjustment.
  

In view of all above the system ensures:

• decrease of the set temperature level deviation as compared to the manual control
  
• minimal fuel rate;
  
• fail-safety and security of equipment functioning;
  
• reducing the level of harmful discharge to the atmosphere;
  
• minimal labor expenditures in controlling the furnaces;
  
• improvement of the staff"s working conditions.
  

Control system structure

Control system for the group of bell-shaped thermic furnaces process technology consists of four identical control panels, one per each furnace and of the operator"s station on the base of PC. All control panels are linked to the operator"s station via Ethernet network.

A control panel is aimed at collecting sensors information and at control for all automated equipment of one furnace in all working modes, including emergency mode. The control panel functions even in case of operator"s station breakdown.

The basis of a control panel is a MicroPC microcontroller manufactured by Octagon Systems. The controlling software for the microcontroller is developed in the Polygon development framework, supplied with the control system. This helps the factory"s specialists to correct and change the controlling algorithms. The software controls three independent controlling circuits: furnace temperature and pressure, recirculation gases temperature. Furnace temperature is regulated by heat supply change due to the pulse-duration modulation of gas-jet "full "heating mode switching time.

There is a local operator"s board on the control panel"s door. It consists of luminescent alphanumeric display and waterproof mini keyboard. The display depicts the values of all the measured parameters. All technological operations (ventilation, kindling, tempering mode initiation, checking device) may be carried out from the local operator"s board.

Operator"s station

Operator"s station is created for displaying four bell-shaped furnaces in a convenient form, for control over their modes, storing and reviewing technological data for each of the furnaces for a long period of time.

Visualization of technological information along with the alert and message generating system gives the operator an opportunity for quick and operative reacting on changes in the process technology.

The option of reviewing long time running processes parameters diagrams and convenient means for debugging ensure finding optimal regulators parameters for maintaining the required quality performance.

The operator"s screen could be divided conditionally into:

• current window;
  
• menu panel;
  
• alert chart.
  

The current window is changed depending on the operator"s choice, alert chart and menu panel are constantly on the screen though the contents of menu is changed displaying the list of possible actions at present moment

The operator can watch the work of all furnaces at once or to look through the detailed information about one chosen furnace.

The screen objects have tips which help the operator"s work making it more convenient.